Python interface for the igraph library

igraph is a library for creating and manipulating graphs. It is intended to be as powerful (ie. fast) as possible to enable the analysis of large graphs.

This repository contains the source code to the Python interface of igraph.

You can learn more about python-igraph on our website.

Installation

$ sudo python setup.py install

See details in Installing Python Modules.

Installation with pip on Debian / Ubuntu and derivatives

Install dependencies

$ sudo apt install build-essential python-dev libxml2 libxml2-dev zlib1g-dev bison flex

and then

$ pip install python-igraph

Compiling the development version

If you have downloaded the source code from Github and not PyPI, chances are that you have the latest development version, which might not be compatible with the latest release of the C core of igraph. Therefore, to install the bleeding edge version, you need to instruct the setup script to download the latest development version of the C core as well:

$ sudo python setup.py develop --no-pkg-config --c-core-url https://github.com/igraph/igraph/archive/master.tar.gz

Contributing

Contributions to python-igraph are welcome!

If you want to add a feature, fix a bug, or suggest an improvement, open an issue on this repository and we'll try to answer. If you have a piece of code that you would like to see included in the main tree, open a PR on this repo.

To start developing python-igraph, follow the steps below (these are for UNIX, Windows users should change the system commands a little).

First, clone this repo (e.g. via https) and enter the folder:

git clone https://github.com/igraph/python-igraph.git
cd python-igraph

Second, build both igraph and python-igraph at the same time:

python setup.py build --c-core-url https://github.com/igraph/igraph/archive/master.tar.gz --no-pkg-config

NOTE: Building requires autotools, a C compiler, and a few more dependencies.

This command creates a subfolder within build which you can insert into your PYTHONPATH to import. You need to move out of the main folder to import because there is a subfolder called igraph too. For instance on Linux:

cd ..
PYTHONPATH=$(pwd)/python-igraph/build/lib.linux-x86_64-3.7:$PYTHONPATH python
>>> import igraph
>>> g = igraph.Graph.Full(10)
...

You can now play with your changes and see the results. Every time you make changes to the python-graph code, you need to rebuild by calling the second step above. After the first build, your igraph C core library is compiled already so rebuilding is much faster.

Notes

Pypy

This version of python-igraph is compatible with PyPy and is regularly tested on PyPy with tox. However, the PyPy version falls behind the CPython version in terms of performance; for instance, running all the tests takes ~5 seconds on my machine with CPython and ~15 seconds with PyPy. This can probably be attributed to the need for emulating CPython reference counting, and does not seem to be alleviated by the JIT.

There are also some subtle differences between the CPython and PyPy versions:

• Docstrings defined in the C source code are not visible from PyPy.

• GraphBase is hashable and iterable in PyPy but not in CPython. Since GraphBase is internal anyway, this is likely to stay this way.